Word problems, with short solutions and "details" that reveal steps in solving number theory, logic, geometry, and more. Scripts include original JavaScript about continued fractions, Apollonius circles, Pythagorean triples, decompositions of sums of squares and of Egyptian fractions, inverse of totient, Diophantine equations, and more. "Topics" introduce concepts in algebra, graph theory, number theory, geometry, and more. Also available in French.